Error in web service: core_group_get_course_groups and core_group_get_course_members

<?php

	$token = '1cea1a5f1049acb07e29f0b26230c149';

	$domainname = 'http://10.0.0.18/moodle';

	$functionname = 'core_group_get_group_members';

	$user1 = new stdClass();

	$user1->groupid = '2';

	$params = $user1;

	/// XML-RPC 

	header('Content-Type: text/plain');

	$serverurl = $domainname . '/webservice/xmlrpc/server.php'. '?wstoken=' . $token;

	require_once('./curl.php');

	$curl = new curl;

	$post = xmlrpc_encode_request($functionname, array($params));

	$resp = xmlrpc_decode($curl->post($serverurl, $post));

	print_r($resp);

?>

<?php

	$token = 'b3fdec752c72ac41f6e6bewe3854c55a';

	$domainname = 'http://10.0.0.18/moodle9';

        $functionname = 'core_group_get_course_groups';

        $params = '2';

        /// XML-RPC CALL 

        header('Content-Type: text/plain');

        $serverurl = $domainname . '/webservice/xmlrpc/server.php'. '?wstoken=' . $token;

        require_once('./curl.php');

        $curl = new curl;

        $post = xmlrpc_encode_request($functionname, $params);

        $resp = xmlrpc_decode($curl->post($serverurl, $post));

        print_r($resp);

?>

array

(

     [faultCode] => 404

     [faultString] => Unknown error

)